Revert "Fixed #25417 -- Added a field check for invalid default values."

This reverts commit 71ebcb85b9.

django/db/models/fields/__init__.py

@@ -203,7 +203,6 @@ class Field(RegisterLookupMixin):
         errors = []
         errors.extend(self._check_field_name())
         errors.extend(self._check_choices())
-        errors.extend(self._check_default())
         errors.extend(self._check_db_index())
         errors.extend(self._check_null_allowed_for_primary_keys())
         errors.extend(self._check_backend_specific_checks(**kwargs))
@@ -280,22 +279,6 @@ class Field(RegisterLookupMixin):
         else:
             return []
 
-    def _check_default(self):
-        if self.has_default():
-            default = self.get_default()
-            try:
-                self.clean(default, None)
-            except exceptions.ValidationError as messages:
-                return [
-                    checks.Error(
-                        "Invalid 'default' value: %s" % message,
-                        hint=None,
-                        obj=self,
-                        id='fields.E008',
-                    ) for message in messages
-                ]
-        return []
-
     def _check_db_index(self):
         if self.db_index not in (None, True, False):
             return [

docs/ref/checks.txt

@@ -141,7 +141,6 @@ Fields
   human readable name)`` tuples.
 * **fields.E006**: ``db_index`` must be ``None``, ``True`` or ``False``.
 * **fields.E007**: Primary keys must not have ``null=True``.
-* **fields.E008**: Invalid ``default`` value.
 * **fields.E100**: ``AutoField``\s must set primary_key=True.
 * **fields.E110**: ``BooleanField``\s do not accept null values.
 * **fields.E120**: ``CharField``\s must define a ``max_length`` attribute.

docs/releases/1.9.txt

@@ -542,9 +542,6 @@ Models
 
 * ``connection.queries`` shows queries with substituted parameters on SQLite.
 
-* Added a new model field check that makes sure
-  :attr:`~django.db.models.Field.default` is a valid value.
-
 * :doc:`Query expressions </ref/models/expressions>` can now be used when
   creating new model instances using ``save()``, ``create()``, and
   ``bulk_create()``.

tests/invalid_models_tests/test_ordinary_fields.py

@@ -1,7 +1,6 @@
 # -*- encoding: utf-8 -*-
 from __future__ import unicode_literals
 
-import decimal
 import unittest
 
 from django.core.checks import Error, Warning as DjangoWarning
@@ -65,22 +64,6 @@ class BooleanFieldTests(IsolatedModelsTestCase):
         ]
         self.assertEqual(errors, expected)
 
-    def test_invalid_default(self):
-        class Model(models.Model):
-            field = models.BooleanField(default='invalid')
-
-        field = Model._meta.get_field('field')
-        errors = field.check()
-        expected = [
-            Error(
-                "Invalid 'default' value: 'invalid' value must be either True or False.",
-                hint=None,
-                obj=field,
-                id='fields.E008',
-            ),
-        ]
-        self.assertEqual(errors, expected)
-
 
 class CharFieldTests(IsolatedModelsTestCase, TestCase):
 
@@ -232,22 +215,6 @@ class CharFieldTests(IsolatedModelsTestCase, TestCase):
         ]
         self.assertEqual(errors, expected)
 
-    def test_invalid_default(self):
-        class Model(models.Model):
-            field = models.CharField(max_length=10, default=None)
-
-        field = Model._meta.get_field('field')
-        errors = field.check()
-        expected = [
-            Error(
-                "Invalid 'default' value: This field cannot be null.",
-                hint=None,
-                obj=field,
-                id='fields.E008',
-            ),
-        ]
-        self.assertEqual(errors, expected)
-
 
 class DateFieldTests(IsolatedModelsTestCase, TestCase):
 
@@ -314,25 +281,6 @@ class DateFieldTests(IsolatedModelsTestCase, TestCase):
     def test_fix_default_value_tz(self):
         self.test_fix_default_value()
 
-    def test_invalid_default(self):
-        class Model(models.Model):
-            field = models.DateField(default='invalid')
-
-        field = Model._meta.get_field('field')
-        errors = field.check()
-        message = (
-            "Invalid 'default' value: 'invalid' value has an invalid date format. It must be in YYYY-MM-DD format."
-        )
-        expected = [
-            Error(
-                message,
-                hint=None,
-                obj=field,
-                id='fields.E008',
-            ),
-        ]
-        self.assertEqual(errors, expected)
-
 
 class DateTimeFieldTests(IsolatedModelsTestCase, TestCase):
 
@@ -471,22 +419,6 @@ class DecimalFieldTests(IsolatedModelsTestCase):
         expected = []
         self.assertEqual(errors, expected)
 
-    def test_invalid_default(self):
-        class Model(models.Model):
-            field = models.DecimalField(max_digits=3, decimal_places=2, default=decimal.Decimal('20.00'))
-
-        field = Model._meta.get_field('field')
-        errors = field.check()
-        expected = [
-            Error(
-                "Invalid 'default' value: Ensure that there are no more than 3 digits in total.",
-                hint=None,
-                obj=field,
-                id='fields.E008',
-            ),
-        ]
-        self.assertEqual(errors, expected)
-
 
 class FileFieldTests(IsolatedModelsTestCase):